An analytical method has been developed for the determination of polynuclear aromatic hydrocarbons (PAH) in sewage sludges, involving solvent extraction with cyclohexane, clean-up of the extract using silica gel thin-layer chromatography (TLC) and final separation of the purified PAH by two-dimensional TLC. Semiquantitative evaluation of sample chromatograms was achieved by comparison with standard chromatographic plates under ultra-violet light. Results are presented for a comparison of extraction procedures, determination of extraction efficiency by two different methods and for the analysis of sewage sludges taken from twelve UK sewage treatment works. The merits and limitations of the analytical scheme are discussed.